Printing apparatus

ABSTRACT

A printing apparatus ( 10 ) includes a carrier ribbon supply tool ( 12 ) and a carrier ribbon take-up spool ( 16 ), a print head ( 22 ) having a plurality of heating elements which are individually addressable and energizable selectively to remove pixels of marking medium from the carrier ribbon ( 14 ) during a printing operation, a first motor ( 13 ) which when the printing apparatus ( 10 ) is operated in a first configuration, moves the print head ( 22 ) during a printing operation relative to a substrate ( 15 ) on which an image is to be printed and when the ( 10 ) is operated in a second configuration, the first motor ( 13 ) moving the carrier ribbon ( 14 ) relative to the print head ( 22 ) during a printing operation, and there being a second motor ( 25 ) which is operative when the printing apparatus ( 10 ) is operated in the first and second configurations to advance carrier ribbon ( 14 ) from which pixels of marking medium have been removed in a previous printing operation, onto the carrier ribbon take-up spool ( 16 ), the printing apparatus ( 10 ) being configurable to either of the first and second printing apparatus ( 10 ) being configurable to either of the first and second configurations.

DESCRIPTION OF INVENTION

This invention relates to a printing apparatus and more particularly toa printing apparatus of the kind which has a print head with a pluralityof heating elements which are individually addressable, e.g. by acomputer control, so that the heating elements may selectively beindividually energised to cause pixels of marking medium to be removedfrom a carrier ribbon during printing, the pixels of marking mediumbeing deposited onto a substrate to form a desired image.

More particularly but not exclusively the invention relates to such aprinting apparatus which is utilised in a manufacturing and/or packagingenvironment, e.g. on a packaging line to print onto packaged orpart-packaged articles which thus are substrates, or onto labels whichare then applied to packaged or part-packaged articles.

High performance such printing apparatus are known which are able toprint at high speed. Such high performance apparatus utilise highperformance print heads, the heating elements of which are able toundergo heating when actuated, and subsequent cooling, more quickly thanlower performance print heads which have longer heating/cooling cycletimes. However, such high performance apparatus require high performancecarrier ribbon to be used, so that the pixels of marking medium can beremoved from the ribbon, i.e. “peeled” from the carrier ribbon, at lowertemperatures compared to lower performance carrier ribbon.

Where there is an established supply chain, purchasers of such highperformance printing apparatus can readily obtain supplies of such highperformance carrier ribbon for use in high performance printingapparatus, but where there is an unreliable supply chain, as highperformance printing apparatus cannot reliably use lower performancecarrier ribbon, where only lower performance carrier ribbon can beobtained, the high performance printing apparatus cannot be used.

This problem is aggravated where printing apparatus of increasinglyhigher performance are being developed.

In different applications, different types of printing apparatus of thekind with which this invention is concerned, may be used. For example inan application where it is possible for the substrate to be stationaryat a print station where the printing apparatus is located, a so calledintermittent printer may be used.

In an intermittent printer, the print head is moved at a printingstation relative to a stationary substrate and carrier ribbon withselected heating elements being heated in each of a plurality of pixelcolumn positions along the carrier ribbon, to form an image. Typicallythe print head is moved towards and into contact with the carrier at thebeginning of printing to urge the carrier ribbon towards the adjacentsubstrate, and the print head is moved away from the carrier andsubstrate at the end of printing. The print head is then returned to astart-of-printing position and the substrate is replaced with freshsubstrate which is to be printed upon, and the carrier ribbon may beadvanced to bring fresh carrier ribbon into position adjacent the printhead for use in subsequent printing.

In an application where the substrate moves past the printing stationcontinuously without stopping, a continuous printer typically is used.

In a continuous printer, the print head is stationary and as thesubstrate moves past the print head, during printing, carrier ribbon ismoved past the print head, usually at about the same speed as thesubstrate. The heating elements of the print head are sequentiallyselectively energised so that pixels of marking medium are depositedonto the moving substrate.

Continuous printers are generally designed for the substrate to movepast the print head in one direction, i.e. right to left, or left toright to match the direction in which the substrate is moved.

Particularly constructed intermittent printers may be used to print oncontinuously moving substrate, where the substrate speed is too greatfor the heating elements of a stationary print head to be heated andcooled fast enough in each column position, to reduce the relative speedbetween the substrate and the print head.

Thus conventionally for each different application, a printing apparatusof a particular configuration is required. Thus for a printing apparatusmanufacturer, it is necessary to produce a wide range of printingapparatus to suit different applications. Where a user changes theconfiguration of a packaging line, for example where the printingapparatus is for use in a manufacturing and/or packaging environment, anexisting printing apparatus may no longer be suitable in there-configured environment, requiring the purchase of an alternativeconfiguration of printing apparatus.

Printing apparatus with which the present invention are concernedtypically are currently made in countries with a high technologyinfrastructure. Where they are used in countries without suchinfrastructure, there are often communication and supply chaindifficulties in establishing and supplying the type of printingapparatus which is required for a particular application and appropriatecarrier ribbon.

In conventional printing apparatus of the kind with which the presentinvention is concerned, the carrier ribbon and much of the carrier feedmechanism, is provided on a cassette which has a supply spool from whichcarrier ribbon is unwound for printing, and a take-up spool onto whichthe carrier ribbon is wound after use. By providing the carrier ribbonon a cassette, there is no need for a user to thread the carrier ribbonaround a ribbon feed path when it is necessary to replenish the carrierribbon, and in the event of ribbon breakage, simply the cassette may bereplaced so as to provide minimal interruption in the printing process.Where the carrier ribbon is broken, the ribbon may be re-threaded sothat its cassette may be re-used, whilst printing may continue.

However, where cassettes are particular to particular printingapparatus, again, where there are under-established supply chaininfrastructures, the printing apparatus can become unusable because thenecessary type of cassette with fresh carrier ribbon, may not readily beavialable.

According to one aspect of the present invention we provide a printingapparatus as set out in claim 1.

Thus the printing apparatus may be configured for either intermittent orcontinuous printing, with the first motor being alternatively used tomove the print head relative to the carrier ribbon, which may bestationary or moving, or to move the carrier ribbon relative to astationary print head.

Preferably, the first motor moves the print head when operated in thefirst configuration and the carrier ribbon when operated in the secondconfiguration, via a transmission, the carrier ribbon being disconnectedfrom the transmission in the first configuration and the print headbeing disconnected from the transmission in the second configuration.

The transmission may include a rotary to linear drive transfer mechanismwhereby in the first configuration the print head is carried by alinearly movable part so as to be moved linearly during a printingoperation along the carrier ribbon, and in the second configuration thecarrier ribbon is entrained around guides on the linearly movable partand around other guides so that as the linearly movable part movesduring a printing operation, the carrier ribbon is moved relative to theprint head.

Thus in the second configuration, the linearly movable part acts as ashuttle to move a small length of the carrier ribbon required forprinting.

When the printing apparatus is operated in the second configuration, andthe substrate moves relative to the print head in a first direction, thelinearly movable part may be moved in a second linear direction oppositeto the first direction to move the carrier ribbon in the same directionas the substrate and vice versa, and where the substrate moves in thefirst direction, inbetween printing operations, a length of the carrierribbon may be moved past the print head which is generally equal to thelength of carrier ribbon used in the preceding printing operation plusthe length of carrier ribbon to be used for the next printing operation.

Thus unlike conventional printers, image printing occurs from unusedcarrier ribbon towards used carrier ribbon.

When the substrate moves relative to the print head in a seconddirection opposite to the first direction, inbetween printing operationsthe carrier ribbon is preferably generally stationary relative to theprint head.

In each configuration preferably there is a peeler device associatedwith the print head which is operable to assist in the removal of pixelsof marking medium from the carrier ribbon. When the apparatus isoperated in the second configuration and the carrier ribbon andsubstrate are moved in the first direction relative to the print headduring a printing operation, the print head and associated peeler devicemay be positioned in a first position such that the carrier ribbon isentrained about the peeler device so as to pass over the peeler deviceduring a printing operation subsequent to passing the print head, andwhen the apparatus is operated in the second configuration and thecarrier ribbon and substrate are moved in the second direction relativeto the print head during a printing operation the print head andassociated peeler device may be positioned in a second position suchthat the carrier ribbon is entrained about the peeler device so as topass over the peeler device during a printing operation subsequent topassing the print head.

In a preferred embodiment, the second motor is coupled to the take-upspool via an overdrive clutch and the second motor drives a drive rolleraround which the carrier ribbon is entrained, whereby the carrier ribbonmay be advanced onto the take-up spool when the drive roller is driven.However alternative drive mechanisms for the second motor mayalternatively be used.

The supply and take-up spools, and guides which guide the carrier ribbonat least partially around a carrier ribbon feed path may be mounted on abase, and a transmission, which may include a rotary to linear drivetransfer mechanism, may also be mounted on the base whereby theapparatus may be re-configurable from the first to the secondconfiguration by disconnecting the transmission from the print head,fixing the print head relative to the base, and entraining carrierribbon around guides on a linearly movable part of the transfermechanism and around guides which are mounted on the base.

When the apparatus is operated in at least the first configuration, theprint head may be moved towards the adjacent carrier ribbon andsubstrate during printing to urge the carrier ribbon towards thesubstrate, and the print head may be moved away from the carrier ribbonand substrate after printing. Although the print head movement towardsand away from the carrier ribbon may be achieved by e.g. one or morepneumatic actuators, where there is no available supply of compressedair, the print head may be moved towards and away from the carrierribbon and substrate at the beginning and end of a priority operation bythe first motor, via mechanical guide means including a cam and track,so that the print head is maintained in its position in which it urgesthe carrier ribbon towards the substrate by the interaction of the camand track.

According to a second aspect of the invention we provide a printingapparatus as set out in claim 10.

The printing apparatus of the second aspect of the invention may haveany of the features of the printing apparatus of the first aspect of theinvention.

According to a third aspect of the invention we provide a printingapparatus as set out in claim 12.

The printing apparatus of the third aspect of the invention may have anyof the features of the printing apparatus of the first or second aspectsof the invention.

According to a fourth aspect of the invention we provide a printingapparatus as set out in claim 14.

The printing apparatus of the fourth aspect of the invention may haveany of the features of the printing apparatus of the first, second orthird aspects of the invention.

According to a fifth aspect of the invention we provide a method ofprinting using a printing apparatus as set out in claim 16.

The invention will now be described with reference to th accompanyingdrawings in which:

FIG. 1 is a side illustrative view of a printing apparatus in accordancewith the invention, in a first configuration;

FIG. 2 is a view similar to FIG. 1 of the printing apparatus in a secondconfiguration;

FIG. 3 is a view similar to FIG. 2 with the apparatus in a secondconfiguration, but for operation in an alternative mode.

FIG. 4 is an illustration of a cam and track arrangement which may beused in a printing apparatus in accordance with the invention.

Referring to FIG. 1 there is shown a printing apparatus 10 in accordancewith the present invention, in a first configuration in which theapparatus 10 is to be used for intermittent printing.

The apparatus 10 includes a base 11 which in this example is plate-like,on which base plate 11 are mounted various components of the apparatus10 including a carrier ribbon supply spool 12 for storing a supply ofcarrier ribbon 14. The carrier ribbon 14 is of the kind which carries athermally active marking medium or ink. Upon the ink becoming heated,the ink softens and may be removed from the carrier and deposited onto asubstrate such as is positioned as indicated at item 15 in the drawing.

The base plate 11 also provides a mounting for a used carrier take-upspool 16 which is coupled to a drive motor 13 via an overdrive clutch sothat the spool 16 may be overdriven to maintain the carrier ribbon taut.The carrier ribbon 14 passes around a ribbon path which in thisconfiguration is provided by a plurality of carrier ribbon guides 17,18, 19, 20, which in this example are rollers, but could be simpleposts, and a drive roller 21, all of which are mounted on the base plate11. The drive roller 21 is driven by the motor 13 via a drive belt 23 inthis example, and the drive roller is a “rogers” roller which isslightly sticky to provide a positive drive to the carrier ribbon 14when the roller 21 is rotated.

A print head 22 is provided which is of the thermal kind having aplurality of individually computer addressable heating elements in anarray, usually a linerar array. When a heating element is selectivelyaddressed, it becomes energised to soften a pixel of marking ink whichmay then be removed from the carrier ribbon 14 and deposited onto thesubstrate 15.

In this configuration, the print head 22 is movable relative to thesubstrate 15 and carrier ribbon 14 which typically would be stationaryrelative to the base plate 11, the heating elements being selectivelyenergised in a plurality of column positions along the carrier ribbon14, so that an image may be printed in the substrate 15. However inanother example, the substrate 15 and carrier ribbon 14 might be movingrelative to the base plate 11 too.

The print head 22 in the example of FIG. 1 moves from left to rightduring a printing operation and immediately after contact with theheating elements of the print head 22, the carrier ribbon 14 is passedover a peeler device which in this example is a peeler roller 24, tofacilitate the removal of the heated and softened pixels from thecarrier ribbon 14. At the end of a printing operation, the print head 22is moved back to the position shown in FIG. 1, and used carrier ribbonis advanced towards the take-up spool 16 by the drive roller 21.

Print head 22 movement is effected by a drive motor 25 through atransmission including a rotary to linear drive mechanism which includesa sprocket 26 which when rotated engages with teeth of a linerarlymovable rack 27 to which, in this configuration, is secured a mounting29 for the print head 22. The print head 22 includes a bracket 30 whichis secured to the linear moveable rack 27 which ensures that the printhead 22 is at an optimal angle relative to the carrier ribbon 14 andsubstrate 15 for removing pixels of marking medium.

Linearly moveable rack 27 movement is guided by a track 31 which ispreferably mounted on the base plate 11.

Just prior to printing, the print head 22 is moved towards the adjacentcarrier ribbon 14 and substrate 15, to urge the carrier ribbon 14 andsubstrate 15 together, as is desirable for efficient pixel transfer.Just after a printing operation, the print head 22 is moved away fromthe adjacent carrier ribbon 14, to facilitate moving the print head 22back to the start-of-print position, and to facilitate advancing theused carrier ribbon 14 towards the take-up spool 16, to enable freshcarrier ribbon 14 from which pixels of ink have not previously beenremoved, to be positioned adjacent the print head 22 ready for the nextprinting operation.

This “towards” and “away from” movement of the print head 22 may beachieved using a pneumatic or other fluid powered actuator. However inenvironments where a ready supply of compressed air or the like is notavailable, a mechanical arrangement may be used as described below withreferences to modifications.

An entire printing operation will now be described.

When a substrate 15 is positioned at a printing station adjacent theprint head 22 as shown, and with the substrate 15 and carrier ribbon 14stationary, relative to the base plate 11, the print head 22 is movedtowards and into contact with the carrier ribbon 14 and substrate 15.The print head 22 is then moved along the carrier ribbon 14 andsubstrate 15 whilst the heating elements of the print head 22 areindividually selectively energised under computer control, to print animage on the substrate 15. When the print head 22 reaches an end-ofprint position, a sensor 32 senses arrival of the print head 22, orrather the linearly movable mounting 29. The print head 22 is then movedaway from the carrier ribbon 14 and substrate 15 and returned to thestart-of-print position while drive roller 21 is actuated to move usedcarrier ribbon 14 towards the take-up spool 16.

The printing apparatus 10 may be reconfigured, or initially configuredin an alternative way, as will be described with reference to FIG. 2. Inthis configuration, the printing apparatus 10 is configured to be acontinuous printer which is arranged to print on moving substrate, asthe substrate 15 passes the stationary print head 22.

In the FIG. 2 configuration, the substrate 15 is moved through theprinting station relative to the print head 22 in a first direction asshown by the directional arrow A. The substrate 15 may be a continuousweb, such as for example a backing carrying labels on which images areto be printed, or discrete articles, such as packages carried on aconveyor, for examples only.

In the FIG. 2 configuration, the mounting 29 for the print head 22 hasbeen disconnected from the rack 27, and is fixed relative to the baseplate 11 in a desired position for printing. The bracket 30 which in theFIG. 1 example, was provided to attach the print head 22 to its mountingis replaced with an alternative bracket 30 a, so that the print head 22is in a correct (first) position for printing in its fixed position.

The carrier ribbon 14 feed path has been changed in as much as thecarrier ribbon 14 has been entrained around a pair of guide rollers 35,36 carried by the rack 27. The carrier ribbon 14 between the two guides17, 18 is entrained about roller 35 carried by the linearly moveablerack 27, and an additional base plate 11 mounted guide 37, and thecarrier ribbon 14 between guides 19 and 20 is entrained around roller36. Moreover, a further pair of guides 38, 39 between the guides 19, 20are mounted on the base plate 11, with the linearly movable rack 27mounted roller 36 between the further pair of guides 38, 39.

During printing, the rack 27 is driven by the sprocket 26 and hencefirst motor 25 from left to right, in the second direction B as seen inthe drawing, i.e. in a direction opposite to the moving substrate 15 onwhich it is desired to print an image.

By virtue of the carrier ribbon 14 being entrained as described aroundthe various base plate 11 mounted guides 17, 37, 18, 19, 38, 39, 20 andthe rack carrier rollers 35, 36, it will be appreciated that as the rack27 moves from left to right in the second linear direction B, carrierribbon 14 adjacent the print head 22 will be moved linearly from rightto left with the substrate 15, through the printing station, past theprint head 22. The linearly movable rack 27 therefore acts as a shuttleto move the carrier ribbon 14 during a printing operation without havingto rotate the drive roller 21, thus to achieve differential movementbetween the print head 22 and carrier ribbon 14 necessary to effectprinting of an image on the moving substrate 15.

Preferably the shuttle rack 27 is moved at a linear speed such that thespeed of the carrier ribbon 14 past the print head 22 generally matchesthe speed of the moving substrate 15 so that there is no or littledifferential movement between the carrier ribbon 14 and the substrate 15during printing, at least when the shuttle 27 has been accelerated up tothe substrate speed.

In this configuration, the sensor 32 which in the FIG. 1 configurationsenses the end-of-printing, is repositioned to sense the shuttle rack 27at the start-of-print position.

At the end of printing it will be appreciated that to the left of theprint head 22, there will be a length of carrier ribbon 14 from whichpixels of ink were removed during the previous print operation. When theshuttle rack 27 is moved back to its start-of-print position, the usedcarrier ribbon 14 will be moved back past the print head 22. Hence toensure that there is fresh carrier ribbon 14 available for the nextprinting operation, the drive roller 21 is required to be rotated tomove a length of fresh carrier ribbon 14 too past the print head 22, atleast equal to that which will be used for the next printing operation.

To minimise carrier ribbon 14 wastage if too much fresh ribbon is movedpast the print head 22 in the second direction opposite B to the firstdirection A in which the carrier ribbon 14 moves during printing, whilstensuring that sufficient fresh carrier ribbon 14 is available so thatover printing of already used carrier ribbon 14 does not occur, carefulcontrol is required. Particularly where the image length of a subsequentprint is not the same as for the previous print, the amount the driveroller 21 is rotated inbetween printing operations may be calculated foreach print. By having the sensor 32 in the position described, it canalways be assured that whatever length of carrier ribbon 14 was movedpast the print head 22 during the previous printing operation, this ismoved back past the print head 22 towards the used carrier ribbon 14take-up spool 16, when the shuttle rack 27 is moved back to itsstart-of-print position.

With minor adjustments to the configuration of the printing apparatus 10of FIG. 2, the apparatus 10 may be configured to operate in analternative mode, namely in which the substrate may move through theprinting station relative to the print head 22 in a second direction B,i.e. from left to right. Such mode of operation will now be describedwith reference to FIG. 3.

The only mechanical differences between the printing apparatus 10 shownin FIGS. 2 and 3, are a) that in the FIG. 3 mode of operation, theposition of the print head 22 is reversed to a second position correctlyto position the array of heating elements of the print head 22appropriately for printing on the left-to-right moving substrate 15(this may be achieved by reversing the print head mounting bracket 30 aas shown at 30 b), and b) the position of the sensor 32 is returned tothe position the sensor 32 occupied in the FIG. 1 configuration.

Of course in the FIG. 3 mode of operation, the shuttle rack 27 is movedfrom right to left during a printing operation, in the first direction Aso that the carrier ribbon 14 adjacent the print head 22 is moved fromleft to right in the same direction as the substrate 15.

At the end of a printing operation, the shuttle rack 27 is moved back toits start-of-print position, and at the same time the drive roller 21may be rotated, so that used carrier ribbon 14 in the ribbon path iswound onto the take-up spool 16. Provided that shuttle rack 27 and driveroller 21 movement is coordinated there is no need for any used or freshcarrier ribbon 14 to be fed back past the print head 22 as the shuttlerack 27 returns to its start-of-print position.

It will be appreciated that the same printing apparatus 10 may thus bealternatively configured to provide an intermittent or continuousprinter, and that when configured as a continuous printer the apparatus10 may print images for whichever of the first and second directions thesubstrate 15 is moving.

By providing a base plate 11 on which the various re-configurablecomponents of the apparatus 10 are mounted, the base plate 11 having allthe necessary mountings provided for the components in their differentpositions, the printing apparatus 10 may readily be reconfigured whennecessary. It is envisaged that the apparatus 10 will be supplied from amanufacturer to a customer in one selected configuration, and may bereadily reconfigured by the customer as desired.

By providing an apparatus 10 in which the carrier ribbon 14 is providedon a simple spool 12, rather than in a cassette mechanism as is commonwith conventional printing apparatus 10, even where supply chains areunpredictable, the printing apparatus is less likely to be renderedunusable due to a lack of availability of an appropriate cassette. Also,so that the apparatus 10 may readily be used with different qualitycarrier ribbons 14, the print head 22 may readily be replaced with analternative performance print head 22. Thus again, where supply chainsare unpredictable, the apparatus 10 is less likely to be renderedunusable through lack of availability of carrier ribbon 14 of a qualityto match the performance of the print head 22.

The printing apparatus 10 is used in conjunction with a computer controlwhich controls the operation of the apparatus 10. The computer may bebuilt into a housing of the apparatus 10, or may be separate andconnected to the apparatus 10 via a direct or network connection.

It will be appreciated that for different printing modes for which theprinting apparatus 10 requires configuring, alternative computercommands would be required for the different printing apparatus 10configurations. Hence software for driving the printing apparatus may beconfigurable for different printing apparatus 10 configurations

Various modifications may be made without departing from the scope ofthe invention. For example, an alternative transmission to the sprocket26 and rack 27 for linearly driving the print head 22 when the apparatus10 is in the first configuration and for driving the shuttle rack 27 andhence carrier ribbon 14 when the apparatus is in the secondconfiguration may be provided. Any other linearly movable part in placeof the rack 27 may be utilised provided that the part can be linearlymoved by the motor 25, preferably via a rotary to linear drivemechanism.

Where a supply of compressed air or the like is unavailable for movingthe print head 22 towards and away from the carrier ribbon 14 andsubstrate 15, if desired a mechanical arrangement may be provided toachieve such movement as indicted in FIG. 4. As the print head 22 isinitially moved by the motor 25 at the start of a printing operation,via the rack 27, the print head 22, which is carried via the bracket 30on the mounting 29 which includes a cam 101, is moved towards thecarrier ribbon 14 and substrate 15, as the cam 101 is moved in a track102 provided on the base 11.

During printing, when the heating elements H of the print head 22 areoperated to print the image by removing the pixels of marking mediumfrom the carrier ribbon 14, the print head 22 is maintained in itsposition in which the carrier ribbon 14 is urged towards the substrate15, by the interaction of the cam 101 and track 102, as the cam 101moves along the track 102. The track 102 is configured so that as thecam 100 continues to move along the track 102, at the end of printingthis causes a movement of the print head 22 away from the carrier ribbon14 and substrate 15 until just before the linear mounting 29 reaches thesensor 32.

The track 102 is configured so that at the beginning of a printoperation, as the mounting 29 commences movement, the cam 101preferentially moves in a first track part 102 a which extends towardsthe carrier ribbon 14 and substrate 15, so that the print head 22 ismoved towards the carrier ribbon 14 and substrate 15 as it moveslinearly.

Movement of the cam 101 in the first track part 102 a, rather than alonga top track part 102 c is assured by providing a step S1 in the bottomof the track 102, and by biasing the cam 101 towards the bottom of thetrack 102 by a spring acting between the mounting 29 and the cam 101.

While the heating elements H are being actuated during image printing,the cam 101 is moved along a second track part 102 b. The depth of thesecond track part 102 b decreases as the cam 101 moves, to a second stepS2 where the print head 22 movement stops. Thus, the cam 101 will bebiased into and enter a third track part 102 c at the step S2.

The first motor 13 will then operate in a reverse direction to move therack 27 in an opposite direction, which in turn will also move themounting 29 and print head 22 linears back to the FIG. 1 position.Because of the step S2 between the second 102 b and third 102 c trackparts, the cam 101 is constrained to move along the third track part 102c rather than back along the second track part 102 b.

The third track part 102 c is configured so that the print head 22 movesaway from the carrier 14 and substrate 15 during such reverse movement.

The depth of the third track part 102 c in the direction along which thecam 101 moves along it, reduces towards the first step 101.

To permit print head 22 movement relative to the mounting 29, springs 31are provided between the rack 27 and the mounting 29 on which the printhead 22 is mounted.

Alternative such mechanical arrangements involving a cam and track areno doubt possible.

Although the base plate 11 construction is preferred, the invention maybe realised with the re-configurable components of the printingapparatus 10 being alternatively mounted e.g. on a chassis or otherbase.

The features disclosed in the foregoing description, or the followingclaims, or the accompanying drawings, expressed in their specific formsor in terms of a means for performing the disclosed function, or amethod or process for attaining the disclosed result, as appropriate,may, separately, or in any combination of such features, be utilised forrealising the invention in diverse forms thereof.

1. A printing apparatus including a carrier ribbon supply spool and acarrier ribbon take-up spool, a print head having a plurality of heatingelements which are individually addressable and energisable selectivelyto remove pixels of marking medium from the carrier ribbon during aprinting operation, a first motor which when the printing apparatus isoperated in a first configuration, moves the print head during aprinting operation relative to a substrate on which an image is to beprinted, and when the apparatus is operated in a second configuration,the first motor moving the carrier ribbon relative to the print headduring a printing operation, and there being a second motor which isoperative when the printing apparatus is operated in the first andsecond configurations to advance carrier ribbon from which pixels ofmarking medium have been removed in a previous printing operation, ontothe carrier ribbon take-up spool, the printing apparatus beingconfigurable to either of the first and second configurations.
 2. Anapparatus according to claim 1 wherein the first motor moves the printhead when operated in the first configuration and the carrier ribbonwhen operated in the second configuration, via a transmission, thecarrier ribbon being disconnected from the transmission in the firstconfiguration and the print head being disconnected from thetransmission in the second configuration.
 3. An apparatus according toclaim 2 wherein the transmission includes a rotary to linear drivetransfer mechanism whereby in the first configuration the print head iscarried by a linearly movable part so as to be moved linearly during aprinting operation along the carrier ribbon, and in the secondconfiguration the carrier ribbon is entrained around guides on thelinearly movable part and around immovable guides so that as thelinearly movable part moves during a printing operation, the carrierribbon is moved relative to the print head.
 4. An apparatus according toclaim 3 wherein when the printing apparatus is operated in the secondconfiguration, and the substrate moves relative to the print head in afirst direction, the linearly movable part is moved in a second lineardirection opposite to the first direction to move the carrier ribbon inthe same direction as the substrate and vice versa, and where thesubstrate moves in the first direction, inbetween printing operations, alength of the carrier ribbon is moved past the print head which isgenerally equal to the length of carrier ribbon used in the precedingprinting operation plus the length of carrier ribbon to be used for thenext printing operation.
 5. An apparatus according to claim 4 whereinwhen the substrate moves relative to the print head in a seconddirection opposite to the first direction, inbetween printing operationsthe carrier ribbon is generally stationary relative to the print head.6. An apparatus according to claim 5 wherein there is a peeler deviceassociated with the print head which is operable to assist in theremoval of pixels of marking medium from the carrier ribbon and when theapparatus is operated in the second configuration and the carrier ribbonand substrate are moved in the first direction relative to the printhead during a printing operation the print head and associated peelerdevice are positioned in a first position such that the carrier ribbonis entrained about the peeler device so as to pass over the peelerdevice during a printing operation subsequent to passing the print head,and when the apparatus is operated in the second configuration and thecarrier ribbon and substrate are moved in the second direction relativeto the print head during a printing operation the print head andassociated peeler device is positioned in a first position such that thecarrier ribbon is entrained about the peeler device so as to pass overthe peeler device during a printing operation subsequent to passing theprint head.
 7. An apparatus according to claim 1 wherein the secondmotor is coupled to the take-up spool via an overdrive clutch and thesecond motor drives a drive roller around which the carrier ribbon isentrained, whereby the carrier ribbon may be advanced onto the take-upspool when the drive roller is driven.
 8. An apparatus according toclaim 1 wherein the supply and take-up spools, and guides which guidethe carrier ribbon at least partially along a carrier ribbon feed pathare mounted on a base, and a transmission which includes a rotary tolinear drive transfer mechanism is also mounted on the base whereby inthe first configuration the print head is carried by a linearly movablepart, the apparatus being re-configurable from the first to the secondconfiguration by disconnecting the transmission from the print head,fixing the print head relative to the base, and entraining carrierribbon around guides on the linearly movable part and around guideswhich are immovable relative to the base.
 9. A printing apparatusaccording to claim 1 wherein when the apparatus is operated in at leastthe first configuration, the print head is moved towards the adjacentcarrier ribbon and substrate during printing to urge the carrier ribbontowards the substrate, and the print head is moved away from the carrierribbon and substrate after printing, and wherein the print head movementtowards and away from the carrier ribbon is achieved as the print headis moved by the first motor by mechanical guide means including a camand track.
 10. A printing apparatus including a carrier ribbon supplyspool and a carrier ribbon take-up spool, a print head having aplurality of heating elements which are individually addressable andenergisable selectively to remove pixels of marking medium from thecarrier ribbon during a printing operation, a first motor to move thecarrier ribbon relative to the print head during a printing operation,and a second motor to advance carrier ribbon from which pixels ofmarking medium have been removed in a previous printing operation, ontothe carrier ribbon take-up spool, wherein the carrier ribbon is movedpast the print head inbetween printing operations to advance used ribbononto the take-up spool in a direction opposite to the direction theribbon is moved during a printing operation, and inbetween printingoperations, a carrier ribbon length is advanced past the print headgenerally equal to the length of carrier ribbon used in the precedingprinting operation plus the length of carrier ribbon to be used for thenext printing operation.
 11. A printing apparatus according to claim 10wherein the printing apparatus is configurable alternatively in firstand second configurations and in the first configuration the firstmotor, during printing, moves the print head relative to a substrate onwhich an image is to be printed, and in the second configuration thefirst motor, during printing, moves the carrier ribbon relative to theprint head.
 12. A printing apparatus including a carrier ribbon supplyspool and a carrier ribbon take-up spool, a print head having aplurality of heating elements which are individually addressable andenergisable selectively to remove pixels of marking medium from thecarrier ribbon during a printing operation, a first motor to move thecarrier ribbon relative to the print head during a printing operation,and a second motor to advance carrier ribbon from which pixels ofmarking medium have been removed in a previous printing operation, ontothe carrier ribbon take-up spool, wherein in a first mode of operationwhen the substrate moves relative to the print head during a printingoperation in a first direction, the carrier ribbon moves in the samedirection as the substrate, and in a second mode of operation when thesubstrate moves relative to the print head during a printing operationin a second direction, the carrier ribbon moves in the same direction asthe substrate, and in the first mode of operation where the substratemoves in the first direction during a printing operation, inbetweenprinting operations, a length of the carrier ribbon is advanced past theprint head which is generally equal to the length of carrier ribbon usedin the preceding printing operation plus the length of carrier ribbon tobe used for the next printing operation, and in the second mode ofoperation when the substrate moves relative to the print head in asecond direction during a printing operation, inbetween printingoperations the carrier ribbon is generally stationary relative to theprint head.
 13. A printing apparatus according to claim 12 wherein theprinting apparatus is configurable alternatively in first and secondconfigurations and in the first configuration the first motor, duringprinting, moves the print head relative to a substrate on which an imageis to be printed, and in the second configuration the first motor,during printing, moves the carrier ribbon relative to the print head.14. A printing apparatus including a carrier ribbon supply spool and acarrier ribbon take-up spool, a print head having a plurality of heatingelements which are individually addressable and energisable selectivelyto remove pixels of marking medium from the carrier ribbon during aprinting operation, the print head being movable towards the adjacentcarrier ribbon and substrate during printing to urge the carrier ribbontowards the substrate, and the print head is moved away from the carrierribbon and substrate after printing, and wherein the print head movementtowards and away from the carrier ribbon is achieved as the print headis moved by the first motor via mechanical guide means including a camcarried by the print head and a track provided on a base relative towhich the print head, in use, moves.
 15. (Canceled)
 16. A method ofprinting using a printing apparatus including a carrier ribbon supplyspool and a carrier ribbon take-up spool, a print head having aplurality of heating elements which are individually addressable andenergisable selectively to remove pixels of marking medium from thecarrier ribbon during a printing operation the carrier ribbon beingmovable relative to the print head during a printing operation, andthere being a motor to advance carrier ribbon from which pixels ofmarking medium have been removed in a previous printing operation, ontothe carrier ribbon take-up spool wherein the method includes moving thesubstrate relative to the print head during a printing operation in afirst direction, and moving the carrier ribbon in the same direction asthe substrate, and moving the carrier ribbon inbetween printingoperations in a second opposite direction, the method including,inbetween printing operations, advancing a length of the carrier ribbonpast the print head which is generally equal to the length of carrierribbon used in the preceding printing operation plus the length ofcarrier ribbon to be used for the next printing operation. 17-19.(Canceled)